1. Field of the Invention
This invention relates to float valves and more particularly to float valves which are designed for use in vapor recovery lines in gasoline storage tank facilities. The float housing is specially designed to prevent the valve from closing when vapors are passing through the valve and to close when the liquid level reaches the float. A special float design permits quick opening and closing the valve.
2. Description of Prior Art
A great amount of hydrocarbon vapor is often generated in hydrocarbon storage tanks, especially when the tanks are nearly empty. Current environmental regulations will require the collection of this vapor when these tanks are filled. Many vapor recovery systems have been proposed and are being used. Some of these systems manifold together the existing vent lines from each tank and collect the vapors through this manifold. To prevent overflow of the contents of one of the tanks into the next tank through this manifold, a valve is required. For proper operation this valve must meet several requirements.
One requirement for this valve is that it cannot close during periods of high vapor velocity or the loading of the tank will be restricted. A second requirement is that the valve seat and float must have a shape which permits proper sealing, yet will not become jammed due to the forces created by having the vapors in a large tank concentrated in a small vent line. A third consideration is that the float must be able to move between its open and its closed position freely and quickly to prevent a minimum amount of liquid from passing through the valve. A fourth consideration is to keep the float properly aligned within its housing so that it will not become stuck during its operation.
No valve is presently known which can provide all of these requirements.